As the first member of Chrysler's first new V-8 family since the 1960s, the
4.7 has more power, less weight, increased fuel efficiency, and lower
emissions than the LA series 318 - a member of sole remaining V-8 family
from the 1960s. A new V-6 and V-10 are also planned, both to be based on the
4.7, in much the same way as the current 3.9 V-6 and V-10 are based on the
LA 318 and 360.
On the Jeep, it will be mated with an all-new, electronically-controlled
transmission with five forward ratios. An alternate second gear ratio will
provide improved performance.
The 4.7 has, on the Jeep, 235 horsepower (over 172 kW) and 295 lb.-ft. (400
Nm) of torque, slightly more power than the 318. It produces 30% less
pollution, noise, vibration, and harshness. Fuel economy is 7% better with
the new four-speed automatic. The engine has more pulling power, faster
initial acceleration, and three miles per gallon better economy.
Buddy Revell pointed out that the new engine is "almost" a Hemi - "the only
reason it isn't called a hemi is because the combustion chambers have a wall
on one side that makes it look kind of like a flat tire. Other than that
everything is in the same arrangement. The valve springs are across from
each other and the spark plug goes right down the middle."
The 4.7 has a cast iron block and two cast aluminum cylinder heads with a
single overhead camshaft per bank and two valves per cylinder. It displaces
4701 cm3 (287 cu in.). A relatively small bore of 3.66 inches (93 mm) helped
reduce overall length of the engine, packaging it for the compact engine bay
of the Grand Cherokee. The stroke is 3.4 inches (86.5 mm).
A natural-gas version for the Charger concept car produces 300 hp.
Breathing features include a new tuned-length runner intake manifold,
free-flowing intake and exhaust ports and fast-burn combustion chambers.
Operating with a high 9.3:1 compression ratio, the engine still only
requires regular-grade fuel.
Lightweight material applications and more efficient engine accessories such
as the alternator, power steering pump and air conditioning compressor
further bolster performance and economy. Aluminum cylinder heads, a hollow
camshaft with sintered steel lobes, magnesium valve covers and a molded
composite intake manifold contribute to an overall weight reduction of 54
pounds (24 kg) compared to the previous 5.2-liter engine.
Drivability is enhanced by variable fuel injection timing, sequential
multi-port injection, a quick-sensing inlet-side positioned thermostat and
coil-on-plug ignition, in which each individual spark plug has its own
secondary ignition coil.
In order to improve fuel economy, the new engine features a patented hybrid
cooling fan system that combines in-line electric and engine-driven fans.
This system allows the engine fan to idle at a very low speed (250-300 rpm.
vs. the typical 650-700 rpm.), decreasing noise and vibration at idle and
low speeds. The newly designed cooling system, with a high efficiency water
pump and a secondary thermostat control, reduces power consumption by 12
percent (6 bhp/4.5 kW).
The new coil-on-plug ignition system, two-stage chain cam drive with
automatic tensioners, premium gaskets and cylinder head mounted fuel
injectors are a few of the basic design features that provide for a greatly
increased engine life. The engine is designed to operate 150,000 miles
(240,000 km) under normal conditions without part replacement other than
normal maintenance items. A new automatic serpentine belt tensioner
increases the average accessory belt life to 100,000 miles (160,000 km).
---------------------------------------------------
Steve St.Laurent
2000 Dakota 4.7L, CC, Soon to be Supercharged
1999 Chebby gone in 2003
1993 Suzuki Tracker (Geo) 1.6L
COMING SOON
2003 Aspiring for a V-10 GTS-R
2003 Dodge Dakota 5.7 Hemi R/T
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